Thanks for the responses guys. The reason I'm comfortable applying to, say, BU or Florida, is that even though I look at them as a safety, I'd be completely happy going there based on some of the research their faculty does.
secander2 - Thanks for linking me to your profile, it really helps. Obviously your GPA is the big difference, I know that is the weakness in my application. I'm hoping that this will be made up for by the fact that I went to a kick-ass undergrad institution, have three very strong rec letters from faculty at that institution, and have a major GPA significantly higher than my regular GPA at around a 3.7 or so (my primary major was math, not physics). I still don't really think I can get into a Cornell-type place, but I'll give one or two of those a shot as a reach school anyway.
physicienne - The reason I think applying to schools lower than my current safeties might be a waste of time is simply that I'm very confident I can be accepted to one of the schools I'm applying to already. I say this because I applied last year to a few schools with a much worse pGRE score, worse letters, and less research experience, so I have reference points based on those results (man, I had no idea what I was doing last year - I was completely in over my head). You are right that astro schools can be tricky because of the small sample sizes involved.
Thanks for the help!